Guest-Mediated Modulation\nof Photophysical Pathways\nin a Coronene Bisimide Cyclophane

The properties and functions of chromophores utilized\nby nature\nare strongly affected by the environment formed by the protein structure\nin the cells surrounding them. This concept is transferred here to\nhost–guest complexes with the encapsulated guests acting as\nan environmental stimulus. A new cyclophane host based on coronene\nbisimide is presented that can encapsulate a wide variety of planar\nguest molecules with binding constants up to (4.29 ± 0.32) ×\n10<sup>10</sup> M<sup>–1</sup> in chloroform. Depending on\nthe properties of the chosen guest, the excited state deactivation\nof the coronene bisimide chromophore can be tuned by the formation\nof host–guest complexes toward fluorescence, exciplex formation,\ncharge separation, room-temperature phosphorescence (RTP), or thermally\nactivated delayed fluorescence (TADF). The photophysical processes\nwere investigated by UV/vis absorption, emission, and femto- and nanosecond\ntransient absorption spectroscopy. To enhance the TADF, two different\nstrategies were used by employing suitable guests: the reduction of\nthe singlet–triplet gap by exciplex formation and the external\nheavy atom effect. Altogether, by using supramolecular host–guest\ncomplexation, a versatile multimodal chromophore system is achieved\nwith the coronene bisimide cyclophane.